The present invention relates to a copper-based polishing composition, a method for manufacturing a semiconductor device, a polishing composition, an aluminum-based metal polishing composition, and a tungsten-based metal polishing composition.
In the step of forming a wiring layer, which is one step in the process for manufacturing a semiconductor device, etch back technique is adopted for the purpose of overcoming the difference in level of its surface. This etch back technique is a manner of forming a trench in a form of wiring in an insulating film on a semiconductor substrate, depositing a Cu film on the insulating film including the trench, using a polishing machine and a polishing composition to polish the Cu film, thereby causing the Cu film to remain only inside the trench to form an embedded wiring layer.
Incidentally, as the polishing composition, hitherto a composition wherein an abrasive grain such as colloidal silica is dispersed into pure water has been used. However, in the case in which the Cu film deposited on the substrate is polished by supplying the polishing composition to a polishing pad of a polishing machine and simultaneously applying a predetermined load to the polishing pad, mechanical polishing caused by the abrasive grain and the polishing pad is merely applied to the Cu film. For this reason, there arises a problem that the polishing rate is low, that is, 10 nm/minute.
On the other hand, J. Electrochem. Soc., Vol. 138. No. 11. 3460 (1991), VMIC Conference, ISMIC-101/92/0156 (1992) or VMIC Conference, ISMIC-102/93/0205 (1993) discloses a composition for polishing a Cu film or a Cu alloy film, comprising a slurry of amine-type colloidal silica, or a slurry wherein K3Fe(CN)6, K4(CN)6 or CO(NO3)2 is added.
However, concerning the aforementioned polishing composition, there is no difference in a rate of etching a Cu film between the step of immersing and the step of polishing. Consequently, if a Cu wiring layer inside the trench contacts the polishing composition after the aforementioned etch back step, the Cu wiring layer is further etched by the polishing composition because there is no difference in the rate of etching the Cu film between the step of immersing and the step of polishing. Therefore, the surface level of the Cu wiring layer inside the trenches becomes lower than the surface of the insulating film. Thus, it becomes difficult that the wiring layer having the same level as the surface of the insulating film is formed, so that its flatness is damaged. Moreover, the embedded Cu wiring layer thus formed has a higher resistance than the Cu wiring layer embedded so as to have the same level as the insulating film surface.
Jpn. Pat. Appln. KOKAI Publication No. 10-44047 describes a polishing slurry, comprising an aqueous medium, an abrasive, an oxidizing agent such as a peroxide, and an organic acid such as lactic acid. The oxidizing agent in this polishing slurry has a function of oxidizing a layer of a metal such as copper on an insulating film to heighten a removing rate in mechanical polishing, and the organic acid has a function of heightening selectivity about the polishing rate of the oxidizing agent.
Jpn. Pat. Appln. KOKAI Publication No. 9-55363 discloses a copper-based metal polishing composition comprising a water-soluble organic acid, such as 2-quinoline carboxylic acid, that is a capable of reaction with copper to produce a copper complex compound which is substantially insoluble in water and has a mechanical strength lower than that of copper; an abrasive grain; an oxidizing agent; and water.